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Eccentric resistance training increases and retains maximal strength, muscle endurance and hypertrophy in trained men

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Abstract

The aim of the present study was to evaluate the effects of different resistance training protocols on muscle strength, endurance, and hypertrophy after training and detraining. Thirty-four resistance-trained males were randomized in concentric-only (CONC), eccentric-only (ECC), traditional concentric-eccentric (TRAD) bench press resistance training or control group. The training volume was equalized among the intervention groups. Bench press of 1-repetition maximum (1RM)/body mass, maximum number of repetitions (MNR), and chest circumference were evaluated at the baseline, after 6 weeks of training, and after 6 weeks of detraining. All intervention groups reported significant 1RM/body mass increases after training (CONC baseline: 1.04 ± 0.06, post-training: 1.12 ± 0.08, p < 0.05; ECC baseline: 1.08 ± 0.04, post-training: 1.15 ± 0.05, p < 0.05; TRAD baseline: 1.06 ± 0.08, post-training: 1.11 ± 0.10, p < 0.05). After detraining, only ECC retained 1RM/body mass above the baseline (1.17 ± 0.07, p < 0.05), while CONC and TRAD returned to baseline values. Only ECC improved and retained MNR (baseline: 22 ± 3; post-training: 25 ± 3, and post-detraining: 25 ± 4, p < 0.05 compared with baseline) and chest circumference (baseline: 98.3 ± 2.4 cm, post-training: 101.7 ± 2.2 cm and post-detraining: 100.7 ± 2.3 cm. p < 0.05 compared with baseline), while no significant changes occurred in both CONC and TRAD. The incorporation of eccentric training can be recommended for counteracting the negative effects of detraining or forced physical inactivity.
ARTICLE
Eccentric resistance training increases and retains maximal
strength, muscle endurance, and hypertrophy in trained men
Giuseppe Coratella and Federico Schena
Abstract: The aim of the present study was to evaluate the effects of different resistance training protocols on muscle strength,
endurance, and hypertrophy after training and detraining. Thirty-four resistance-trained males were randomized in concentric-
only (CONC), eccentric-only (ECC), traditional concentric–eccentric (TRAD) bench press resistance training or control group. The
training volume was equalized among the intervention groups. Bench press of 1-repetition maximum (1RM)/body mass, maxi-
mum number of repetitions (MNR), and chest circumference were evaluated at the baseline, after 6 weeks of training, and after
6 weeks of detraining. All intervention groups reported significant 1RM/body mass increases after training (CONC baseline: 1.04 ±
0.06, post-training: 1.12 ± 0.08, p< 0.05; ECC baseline: 1.08 ± 0.04, post-training: 1.15 ± 0.05, p< 0.05; TRAD baseline: 1.06 ± 0.08,
post-training: 1.11 ± 0.10, p< 0.05). After detraining, only ECC retained 1RM/body mass above the baseline (1.17 ± 0.07, p< 0.05),
while CONC and TRAD returned to baseline values. Only ECC improved and retained MNR (baseline: 22 ± 3; post-training: 25 ± 3,
and post-detraining: 25 ± 4, p< 0.05 compared with baseline) and chest circumference (baseline: 98.3 ± 2.4 cm, post-training:
101.7 ± 2.2 cm and post-detraining: 100.7 ± 2.3 cm. p< 0.05 compared with baseline), while no significant changes occurred in both
CONC and TRAD. The incorporation of eccentric training can be recommended for counteracting the negative effects of
detraining or forced physical inactivity.
Key words: bench press, 1RM, maximum number of repetitions, detraining, chest circumference, strength endurance.
Résumé : Cette étude a pour objectif d’évaluer les effets de divers protocoles d’entraînement contre résistance sur la force
musculaire, l’endurance et l’hypertrophie, et ce, a
`la suite d’un entraînement et d’un désentraînement. On répartit aléatoire-
ment 34 hommes entraînés contre résistance dans quatre groupes : développé-couché en miométrie (« CONC »), en pliométrie
(« ECC »), miométrie-pliométrie classique (« TRAD ») et contrôle (« CONC »). On égalise le volume d’entraînement d’un groupe a
`
l’autre. On évalue répétition maximale (« 1RM »)/masse corporelle au développé-couché, le nombre maximal de répétitions
(« MNR ») et le tour de poitrine au début, après 6 semaines d’entraînement et après 6 semaines de désentraînement. Après les
6 semaines d’entraînement, tous les groupes a
`l’entraînement présentent une augmentation significative de 1RM/masse corpo-
relle (CONC début : 1,04 ± 0,06, après l’entraînement : 1,12 ± 0,08, p< 0,05; ECC début : 1,08 ± 0,04, après l’entraînement : 1,15 ±
0,05, p< 0,05; TRAD début : 1,06 ± 0,08, post : 1,11 ± 0,10, p< 0,05). Après la période de désentraînement, seul le groupe ECC
présente un 1RM/masse corporelle au-dessus de la valeur au départ (1,17 ± 0,07, p< 0,05), les groupes CONC et TRAD reviennent
aux valeurs du départ. Seul le groupe ECC améliore et maintient le MNR (début : 22 ± 3; après l’entraînement : 25 ± 3; après le
désentraînement : 25 ± 4, p< 0,05 comparativement au début) et le tour de poitrine (début : 98,3 ± 2,4 cm; après l’entraînement :
101,7 ± 2,2 cm et après le désentraînement : 100,7 ± 2,3 cm, p< 0,05 comparativement au début); dans les groupes CONC et TRAD,
on ne note aucune modification significative. On pourrait recommander l’intégration de l’entraînement en pliométrie pour
contrer les effets négatifs du désentraînement ou de l’inactivité physique forcée. [Traduit par la Rédaction]
Mots-clés : développé-couché, 1RM, nombre maximal de répétitions, désentraînement, tour de poitrine, endurance a
`la force.
Introduction
Resistance training is a great stimulus for increasing muscle
strength and hypertrophy. Traditional resistance training proto-
cols use consecutive eccentric–concentric cycles. However, the
importance of the eccentric phase for increasing muscle strength
was previously highlighted (Dudley et al. 1991). Furthermore, a
meta-analysis showed that eccentric-only versus concentric-only
training induced greater total strength (i.e., the sum of concentric,
isometric, and eccentric peak torque) and muscle hypertrophy
adaptations (Roig et al. 2009). However, the studies considered in
the meta-analysis used different training devices (e.g., isokinetic
dynamometer or dynamic constant external resistance), such as
different training-load volumes. Particularly, matching the differ-
ent training protocols for the session load volume (Coratella et al.
2015a) could help trainers to discriminate the effectiveness of
each training modality. Indeed, when the total work was matched,
similar increases in muscle strength and hypertrophy resulted
after concentric-only versus eccentric-only resistance training (Moore
et al. 2012). In addition, similar relative exercise loads (80% of
concentric vs. eccentric 1-repetition maximum (1RM)), resulted in
similar increases in muscle volume (Franchi et al. 2014). There-
fore, as recently reviewed (LaStayo et al. 2014), the role of exercise
modality for increasing the muscle size remains controversial. In
addition, while eccentric-only and concentric-only based training
protocols have been compared (see (Roig et al. 2009) for a detailed
meta-analysis), the most used method in the field, i.e., traditional
eccentric–concentric exercise, has been rarely compared.
Functional performance improvements are often related to
strength training adaptations. The maximum number of repeti-
Received 6 June 2016. Accepted 8 August 2016.
G. Coratella and F. Schena. Department of Neurological, Biomedical and Movement Science, University of Verona, via Casorati 43, 37131, Verona, Italy.
Corresponding author: Giuseppe Coratella (email: giuseppe.coratella@univr.it.).
Copyright remains with the author(s) or their institution(s). Permission for reuse (free in most cases) can be obtained from RightsLink.
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tions performed using submaximal load has been previously mea-
sured for indicating muscle endurance (Maia et al. 2014;Walker
et al. 2013). Previous studies showed that strength training in-
creased the maximum number of repetitions (Ribeiro et al. 2014;
Walker et al. 2013). The maximum number of repetitions involves
both metabolic (Mujika and Padilla, 2001) and neural adaptations
(Smilios et al. 2010). Compared with concentric-only, the eccentric-only
exercise resulted in greater cortical activation (Fang et al. 2004)
and greater metabolic efficiency (Vogt and Hoppeler 2014). It is
conceivable that the different neural and metabolic engagements
in concentric-only, eccentric-only, or traditional concentric–eccentric
exercises could lead to different adaptations in muscle endurance.
However, to our knowledge, no direct comparison concurrently
investigated the effects of different resistance exercise modalities
on muscle endurance.
The cessation of training (i.e., detraining) is linked to decreases
in both physiological and functional muscle characteristics. Pre-
vious studies showed that traditional resistance training retained
maximal strength increases (Correa et al. 2013;Fatouros et al.
2005). Similarly, previous studies showed that both eccentric-only
(Housh et al. 1996a) and concentric-only (Housh et al. 1996b) resis-
tance training protocols both increased and retained maximal
strength. The mechanisms underlying the muscle strength, hy-
pertrophy, and endurance retention could depend on both neural
(Fang et al. 2004) and cellular (Bruusgaard et al. 2010) factors.
Eccentric-only exercise is known to induce muscle damage and to
confer muscle protection (i.e., the repeated bout effect) (Coratella
and Bertinato 2015). Such a long-lasting protection involved de-
layed extra-cellular matrix adaptations, which can be partially
responsible even for the retention of the training-induced adap-
tations (Hyldahl et al. 2015).
The bench press is one of the most common and effective exercises
for increasing upper body strength and hypertrophy. Although the
bench press involves several upper body muscles, increases in the
size of the chest muscles is one of the main training-induced adap-
tations (Yasuda et al. 2010). In addition, the chest circumference, the
upper arms cross-sectional area and the percentage of fat are all
predictors for the bench press 1RM and they can be used as indirect
markers of muscle hypertrophy (Mayhew et al. 1991). Among these
aforementioned markers, the chest circumference is the most easily
assessable in field, as it does not require the use of laboratory devices
or sophisticated formulas.
Several athletes or amateurs incorporate resistance training in
their workouts. The bench press is included in most strength or
fitness programs, traditionally exercised in concentric–eccentric
protocols. However, the concentric-only or eccentric-only training
protocols are rarely performed within a field-based context, while
they have been largely investigated in laboratory settings. There-
fore, the primary aim of the present study was to evaluate the
retention of maximal strength, maximum number of repetitions,
and chest circumference adaptations after 6 weeks of detraining
subsequent to concentric-only, eccentric-only, or traditional concentric-
eccentric bench press training in resistance-trained men. The
secondary aim was to evaluate if the training-induced changes
depend on the exercise modalities. In the first instance, it has
been conceived that eccentric-only training can successfully re-
tain the training-induced adaptations. In addition, it has been
conceived that despite the different training modalities, the matched-
volume protocols can lead to similar training-induced adaptations.
Materials and methods
Study design
This study was a parallel, 4-groups, pre-/post-training, random-
ized controlled trial. Using a restricted blocked randomization
(computer-generated sequence), the participants were random-
ized into 4 groups: concentric-only (CONC), eccentric-only (ECC),
traditional concentric–eccentric training (TRAD) and control group
(CON). One of the researchers without any contact or knowledge of
the participants completed the allocation and randomization of
groups. Therefore, no allocation concealment mechanisms were
necessary.
Procedures
The present investigation lasted 15 weeks. Participants were
evaluated at week 1, week 8, and week 15. The intervention period
lasted from week 2 to week 7 and the detraining period from
week 9 to week 14. During both training and detraining, partici-
pants were asked to refrain from any other form of strenuous
physical activity. In addition, the detraining period corresponded
to the summer holidays, to avoid as much as possible any chance
of training. On a weekly basis, the operators reminded partici-
pants to avoid any other form of resistance training for the entire
period of the study. Both training and testing sessions were as-
sessed using a flat bench press (Technogym, Cesena, Italy).
Participants
Thirty-four healthy, resistance-trained, sport-science student
males with a minimum of 3 years of experience in resistance
training (age: 26 ± 3.7 years; body mass: 85.4 ± 11.4 kg; height 1.83 ±
0.11 m) volunteered for this study. We included only males who
were able to perform a bench press 1RM equal or greater than
their body-mass (Table 1). Upper joint diseases as well as muscular
injuries were considered as exclusion criteria. In addition, we
excluded males who regularly used supplementation in the pre-
vious 3 months. The participants signed a written informed con-
sensus, which described the procedures in detail, and the Ethics
Committee of the University of Verona approved the present
study.
Intervention
The training volume load was equalized among the 3 interven-
tion groups. We matched the repetition number, the training load
(considered as percentage of 1RM), and the time under tension was
3 s and it was equal for each phase (concentric or eccentric)
(McBride et al. 2009). Therefore, for each training session, ECC
performed 5 sets × 6 repetitions at 120% of 1RM; CONC performed
6 sets × 7 repetitions at 85% of 1RM; TRAD performed 4 sets ×
5 repetitions at 90% of 1RM at the bench press, while CON did not
train. During each repetition performed in ECC, 2 operators lifted
the bar to relieve each participant from the concentric phase
(Coratella et al. 2015b). Similarly, 2 operators lowered the bar dur-
ing each repetition performed in CONC to relieve each participant
from the eccentric phase (Housh et al. 1996b). Participants in
TRAD performed both phases without the help of any operator.
Table 1. Anthropometric and performance characteristics at baseline are reported for each group.
Body
mass (kg) Height (m) 1RM (kg) 1RM/body mass
Maximum
Nrepetitions
Chest
circumference
ECC 86.6±14.3 1.84±0.09 93.8±18.3 1.08±0.04 22.1±3.2 98.3±5.6
CONC 84.6±8.2 1.82±0.08 88.6±9.9 1.05±0.06 25.4±3.8 101.2±5.0
TRAD 84.4±14.2 23.9±4.2 88.7±12.4 1.04±0.08 24.0±4.7 102.8±10.2
CON 86.1±9.2 26.1±4.9 89.0±6.2 1.04±0.06 24.4±3.2 98.3±5.6
Note: No significant between-group difference was found. 1RM, 1-repetition maximum; CON, control; CONC,
concentric-only; ECC, eccentric-only; TRAD, traditional concentric–eccentric.
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Each set was separated by 3 min of passive recovery. The interven-
tion lasted 6 weeks, twice a week, for a total of 12 sessions. Each
session was separated by at least 2 days. After the post-training
testing session, participants did not train for 6 weeks.
To keep the exercise technique similar among the participants,
participants were instructed to exercise using the same relative
bar handgrips distance. Therefore, hands were placed on the bar
at a distance that facilitated approximately a 90° angle between
arms and forearms, when the bar is on the chest, approximately
one-half length of sternum.
Bench press 1RM/body mass
The bench press 1RM was tested on a gym device (Flat bench
press, Technogym, Cesena, Italy). The testing protocol started with a
standardized warm-up, consisting of 2 sets × 15 repetitions with a
load equal to 50% of the person’s body mass. This protocol was
based on the following formula (Brzycki 1993):
predicted 1RM load/1.0278 (0.0278 · n)
where the load is in kg, the 90% of the predicted 1RM was used as
an initial 1RM attempt, and nis the number of executed repeti-
tions. Afterwards, additional load of 2.5 kg was added until sub-
jects failed to lift the bar. Two minutes of passive recovery separated
each trial. Each participant received standardized encourage-
ments by the operators. Bench press 1RM/body mass was recorded
and analyzed.
Bench press maximum number of repetitions
Based on 1RM measurements, after 60 min of passive rest, par-
ticipants performed a single set up to failure of bench press at 50%
of their previously recorded 1RM. They were instructed to main-
tain the time under tension equal to 1.5 s for both concentric and
eccentric phases. A visual chronometer feedback was provided to
help the participants to maintain the proper repetition pace. The
task ended when participants failed to properly lift the bar for
2 consecutive repetitions within the set time under tension. Op-
erator provided standardized encouragements to each participant.
Chest circumferences
The participants stood with arms slightly abducted, permitting
the tape to be passed around the chest. The chest girth was mea-
sured at the level of mesosternal. The measurement was taken at
the end of normal respiration (Stewart et al. 2001). Each measure-
ment was repeated twice and the mean was inserted in data anal-
ysis. If the 2 measures differed by more than 5%, a third measurement
was performed. Same operator performed all measurements.
Statistical analysis
The statistical analysis was performed using IBM SPSS (version
20.0; IBM Corp., Armonk, N.Y., USA). The normality of the distri-
bution was analyzed using Shapiro–Wilk test. The sphericity as-
sumption was analyzed using the Mauchly test. Test–retest reliability
was measured using Cronback-index. The variations of the de-
pendent parameters (bench press 1RM/body mass, maximum
number of repetition and chest circumference) were analyzed
using mixed-factorial repeated measures ANOVA (time × group).
Post hoc analysis using Bonferroni’s correction was then per-
formed to calculate main effect for group (4 levels: ECC, CONC,
TRAD, and CON) and time (3 levels: baseline, post-training, and
after detraining). Significance was set at p< 0.05. Data are re-
ported as means ± SD and change scores are reported with confi-
dence interval (CI) 95% and
2
.
Results
Bench press 1RM/body mass
A time × group interaction (p< 0.001) was found for the bench
press 1RM/body-mass. There was a main effect for time (p< 0.001)
and a trend (p= 0.055) for group. Post hoc analysis showed 1RM/
body-mass increases over time from baseline to post-training in
CONC (0.07 ± 0.01, CI95% 0.04 to 0.10, p< 0.001,
2
= 0.589), in ECC
(0.07 ± 0.01, CI95% 0.04 to 0.10, p< 0.001,
2
= 0.597), and in TRAD
(0.05 ± 0.01, CI95% 0.02 to 0.08, p= 0.001,
2
= 0.437) (Fig. 1).
However, 1RM/body mass increases remained greater than base-
line after detraining only in ECC (0.09 ± 0.01, CI95% 0.05 to 0.012,
p< 0.001,
2
= 0.698), while both CONC and TRAD returned to
values similar to baseline. CON did not show any change. No
between-group differences resulted at baseline. After training,
1RM/body mass resulted greater in ECC compared with CON (0.11 ±
0.04, CI95% 0.01 to 0.20, p= 0.027,
2
= 0.263). After detraining ECC
resulted in greater 1RM/body mass compared with CON (0.13 ±
0.04, CI95% 0.02 to 0.024, p= 0.011,
2
= 0.349) and to CONC (0.11 ±
0.04, CI95% 0.01 to 0.21, p= 0.034,
2
= 0.174) but not to TRAD,
(0.11 ± 0.04, CI95% –0.00 to 0.21, p= 0.058,
2
= 0.111).
Maximum number of repetitions
A time × group interaction (p= 0.042) was found for the bench
press maximum number of repetitions. There was a main effect
for time (p= 0.017), but not for group (p= 0.554). Post hoc analysis
showed increases over time from baseline to post-training only in
ECC (3.0 ± 0.7, CI95% 1.1 to 4.8, p= 0.001,
2
= 0.412) (Fig. 2), In
addition, such increases were retained after detraining compared
with baseline (3.1 ± 1.0, CI95% 0.5 to 5.6, p= 0.014,
2
= 0.304).
Neither CONC, TRAD, nor CON showed any change.
Chest circumference
Test–retest reliability resulted in a Cronbach-= 0.910. A time ×
group interaction (p= 0.014) was found for the chest circumfer-
ence. There was a main effect for time (p< 0.001) but not for group
(p= 0.471). Post hoc analysis showed increases over time from
baseline to post-training only in ECC (3.3 ± 0.6, CI95% 1.7 to 4.8,
p< 0.001,
2
= 0.488) (Fig. 3). The chest circumference remained
above the baseline in ECC after detraining (2.4 ± 0.6, CI95% 0.8 to
3.8, p= 0.001,
2
= 0.417). Neither CONC, TRAD, nor CON showed
any significant change.
Discussion
The present study investigated the effectiveness of different
bench press resistance training protocols on muscle strength, en-
Fig. 1. The time-course of bench press 1RM/BM is shown for each
intervention group. Compared with baseline, greater 1RM/BM resulted
in ECC, CONC, and TRAD post-training. After detraining, 1RM/BM
resulted significantly greater than baseline only in ECC; CONC, and
TRAD showed significant 1RM/BM decreases compared with post-training,
resulting in values similar to baseline. 1RM/BM, 1-repetition maximum/
body mass; CON, control; CONC, concentric-only; ECC, eccentric-only;
TRAD, traditional concentric–eccentric. *, p< 0.05; †, p< 0.05
compared with CON post-training; ‡, p< 0.05 compared with CONC
and CON detraining.
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durance, and hypertrophy increases and retention. The primary
outcomes highlighted that ECC was the only training modality
that preserved the increases in maximum strength after 6 weeks
of detraining in resistance-trained men. In addition, only ECC
improved and retained the maximum number of repetitions at
50% of 1RM and the chest circumference. Finally, all the training
protocols, matched for the volume load, similarly improved the
bench press 1RM/body mass in trained men.
The present outcomes highlighted that only ECC increased and
retained the bench press 1RM/body mass after detraining. The
superiority of the eccentric-only versus concentric-only or tradi-
tional resistance training in strength retention is debatable. The
importance of eccentric exercise for promoting the retention of
strength gains has been documented in literature. Eccentric-only
training was shown to be a great stimulus for retaining strength
increases (Housh et al. 1996a). In addition, knee extensors isokinetic
peak torque remained above the baseline values after 3 months
of detraining following 10 weeks of eccentric-only training (Blazevich
et al. 2007). Furthermore, after concentric-only training versus
traditional training, the detraining seemed to have a detrimental
effect for the strength gain resulted after the concentric-only
training (Dudley et al. 1991). However, other studies showed that
strength retention is not a peculiarity only of the eccentric-only
training. In the same above-mentioned study, the authors also
showed that concentric-only training was able to retain strength
increases after detraining (Blazevich et al. 2007). Similarly, the
knee extensors 1RM improvements induced by concentric-only
training were unaffected by 8 weeks of detraining (Housh et al.
1996b). In addition, traditional resistance training was shown to
be a proper stimulus for increasing the muscle strength and for
retaining it after detraining (Correa et al. 2013). Due to such mul-
tiplicity, it is not possible to state that the strength retention
could depend on the exercise performed during the training pe-
riod. However, our results seemed to confirm the superiority of
ECC compared to CONC and TRAD, in agreement with the studies
that supported the superiority of eccentric-only exercise.
The mechanisms underlying the overall strength retention are
not fully understood. A possible explanation could be that during
the training period, additional nuclei from the satellite cells are
added into the muscle fibres throughout the fusion process, stim-
ulating the increasing in protein synthesis (Bruusgaard et al.
2010). After the end of the training, such nuclei remained into the
muscle cell for at least 3 months. In such a way, the muscle is able
to develop a sort of “memory”, useful both to prevent atrophy
(and consequent decreases in strength) and to get quicker adapta-
tions after retraining (Bruusgaard et al. 2010). However, such
mechanism has been recently debated (Gundersen 2016) and it
cannot explain the greater strength retention that resulted in
ECC. The extra-cellular matrix can be defined as a bridge for the
transmission of force from the myofibres to the tendons (Grounds
et al. 2005). Interestingly, the extra-cellular matrix plasticity could
play a key role for the strength retention. While no difference in
collagens’ upregulation gene responses occurred after 4 days of
concentric-only versus eccentric-only short-term training (Heinemeier
et al. 2007a), a more recent study showed for the first time that the
extra-cellular collagens’ upregulation occurred 27 days (but not
2 days) after repeated eccentric-only exercise (Hyldahl et al. 2015).
It can be speculated that such a delayed stimulus could be par-
tially responsible for the strength retention that resulted only in
ECC. A further explanation involves neural adaptations. Neural
cortical adaptations have been suggested to be partly responsible
for strength retention, although the physiological training in-
duced changes could be dissipated (Gabriel et al. 2006). Compared
with concentric-only, eccentric-only exercise involves larger cor-
tical areas during maximal tasks (Fang et al. 2004). As hypothe-
sized by the same authors, increasing the neural control of the
eccentric exercise contributes to avoid muscle damage (Fang et al.
2004). Indeed, it is known that performing eccentric-only exercise
protects muscle from further damage following the first session
(Coratella and Bertinato 2015). The repeated bout effect can last up
to several months, during which participants did not train
(Nosaka et al. 2001). Therefore, it can be speculated that ECC could
be involved in greater and longer lasting neural cortical adapta-
tions. Finally, it has been shown that strength retention depends
on the intensity performed during the resistance training (Fatouros
et al. 2005). In addition, resistance training showed similar electro-
myography (EMG) signal increases after eccentric-only or concentric-
only isokinetic training (Carvalho et al. 2014). However, the same
authors observed more significant neural adaptations after eccentric-
only compared with concentric-only, probably depending on the
greater torque exerted during ECC. Although both TRAD and
CONC were exercised at high-intensity loads, the greater supramaximal-
intensity load performed in ECC could have favourably influenced
the strength retention. In summary, it can be speculated that the
strength retention, which resulted only in ECC, could depend on
both cellular and neural long-lasting adaptations.
Similarly to the previous data, only ECC showed increases in
chest circumference, which remained significantly above the
baseline after detraining. The anabolic effect of resistance train-
ing depends in first instance on its capacity to stimulate anabolic
Fig. 2. The time-course of maximum number (N) of repetitions is
shown for each intervention group. Post hoc comparison showed
that only ECC increased and retained maximum number of
repetitions after both post-training and detraining compared with
baseline. CON, control; CONC, concentric-only; ECC, eccentric-only;
TRAD, traditional concentric–eccentric. *, p< 0.05.
Fig. 3. The time-course of chest circumference is shown for each
intervention group. Post hoc comparison showed that only ECC increased
and chest circumference after both post-training and detraining
compared with baseline. CON, control; CONC, concentric-only; ECC,
eccentric-only; TRAD, traditional concentric–eccentric. *, p< 0.05.
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hormones such as growth hormone or bioavailable testosterone.
However, the postexercise elevation in hormones is still debatable
and their role still remains to be proved (Schoenfeld 2013). It has
been showed that traditional versus enhanced-eccentric resis-
tance exercise (Yarrow et al. 2007) or short-term training (Yarrow
et al. 2008) led to a similar growth hormone and bioavailable blood
concentration increases in untrained men. However, enhanced-
eccentric training resulted in lower volume load compared with
the traditional protocol (Yarrow et al. 2008). Therefore, similar GH
and BT serum concentrations were found with different load vol-
umes. It can be speculated that equalizing the load volume could
have resulted in a greater anabolic response in ECC. However, it
remains to be proved. In addition, greater insulin-like growth
factor and mechano-growth factor gene expressions were induced
by eccentric-only compared with concentric-only short-term training
(Heinemeier et al. 2007a). Similarly, the same abovementioned
authors found decreases in muscle myostatin messenger RNA after
eccentric-only versus concentric-only training (Heinemeier et al.
2007b). Conversely, comparing eccentric-only versus concentric-
only training, other studies did not show any differences in pro-
tein synthetic response (Franchi et al. 2015) or protein kinase B
and p70 s6 kinase (Cuthbertson et al. 2006) gene expressions. In
addition, it is well known that the aforementioned mechanisms
can last up to several weeks after the end of the training (Bruusgaard
et al. 2010). Therefore, the possible mechanisms underlying the
different hypertrophy responses and retention induced by eccentric-
only versus concentric-only or traditional training modalities are
still controversial.
The maximum number of repetitions exercised at 50% 1RM in-
creased after ECC training and it remained above the baseline
level after detraining. Focusing on the detraining, it has been
shown that the central neural drive is reduced within a fatiguing
strength-endurance task (Walker et al. 2012). In addition, during a
submaximal task, the EMG activity increases for maintaining the
demanded power output, with a reduction in efficiency (Smilios
et al. 2010). Finally, the eccentric contraction resulted in larger
cortical activation (Fang et al. 2004). Therefore, it can be specu-
lated that ECC could have led to an increased and longer lasting
neural drive, which can also result in a greater efficiency turned
into a later fatigue. Furthermore, compared with the maximal
strength, the maximum number of repetition depends also on
metabolic and energetic factors. The enzymatic activity, the mus-
cle capillarization, the mitochondrial ATP production, the muscle
fibre characteristics, and the myoglobin concentration are all in-
volved in the enhancement or the detriment of the submaximal
continuous force production (Mujika and Padilla, 2001). While
several studies showed a greater number of maximum repetitions
after strength training using different traditional exercise proto-
cols (Ribeiro et al. 2014;Maia et al. 2014;Walker et al. 2013), it is
not proven if the intensity or the contraction modality exercised
during the training could influence it. It can be speculated that
ECC could have improved the mechanical efficiency and conse-
quently the muscle endurance (Vogt and Hoppeler 2014). To our
knowledge, no study concurrently compared the retention of the
maximum number of repetitions in response to different resis-
tance training modalities. Hence, it is hypothesized that both
neural and metabolic stimuli could be involved in both increasing
and specially retaining the maximum number of repetitions.
The present outcomes showed similar training-induced strength
increases after all type of intervention. The greater effectiveness
of eccentric-only versus concentric-only training has already been
reviewed (Roig et al. 2009). However, the studies selected for the
meta-analysis used different session intensities or volume. In ad-
dition, traditional resistance training is also known to be effective
for promoting strength increases (Correa et al. 2013). However, the
volume load plays a key role in the strength training-induced
adaptations (Franchi et al. 2014). Therefore, although there were
different exercise modalities and intensities used in the present
study, it is confirmed that similar volume loads induced similar
adaptations (Coratella et al. 2015a).
The present investigation appears to include some limitations.
First, we matched the training volume among the intervention
groups using the volume load method (i.e., repetitions × external
load (kg)). Total work (i.e., force (N) × displacement (m)) is the most
appropriate method to quantify resistance exercise volume, al-
though it is acknowledged that it is not easy to assess (McBride
et al. 2009). However, the same authors stated that the major
limitations of volume load occur when external load is absent,
(e.g., power exercise protocols) and when time under tension is
not taken in account. By equalizing the time under tension (3 s for
concentric and eccentric phases), the volume load could be a rea-
sonable alternative to total work. Second, we did not record the
nutritional intake during the entire investigation period. Even if
nonsignificant body mass changes occurred, it may have con-
founded the results. Third, we did not record muscle damage
markers. Exercise-induced muscle damage could have impaired
the participant’s capacity to properly perform the resistance
training, particularly in the first training sessions. However, a
previous study showed that resistance-trained men were slightly
affected by muscle damage occurring after the bench press exer-
cise (Meneghel et al. 2014). Therefore, we are confident that all
training sessions were properly performed. Fourth, detecting the
EMG signal can provide news insight the muscle activity adapta-
tions after training and particularly detraining. Finally, we tested
the strength changes using concentric 1RM. It is acknowledged
that such a test could not be specific for the eccentric-only exer-
cise, as the eccentric-1RM could be. Therefore, the lack of between-
groups differences in strength training-induced adaptations could
possibly depend also on a nonspecific eccentric test.
In summary, we showed that ECC was the only resistance pro-
tocol able to retain the strength increases after 6 weeks of detrain-
ing in resistance trained men. In addition, only ECC increased and
preserved the maximum number of repetitions and the chest
circumference.
Conflict of interest statement
The authors declare that there are no conflict of interest.
Acknowledgements
Authors are grateful to all participants that volunteered for this
study. Authors want to thank Andrea Bertinato BSc for his pre-
cious help in data collection.
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... This is important, since it will give valuable information e.g., what is the time duration of the retention, since a prolonged detraining period will lead to more drastic decreases in strength and/or muscle mass (e.g. Coratella and Schena, 2016;Coratella et al., 2021). In addition, there ...
... Received: 07 February 2022 / Accepted: 25 March 2022 / Published (online): 04 April 2022 may be some differences in the trainability of muscle strength and mass, time duration of retention between the upper and lower body muscles as well as possible differences between men and women. Coratella and Schena, (2016) compared three groups of men who performed volume-matched ECC only, CON only, or traditional (including both phases) bench press training for 6 weeks. They reported that all groups produced similar increases in 1RM strength. ...
... It also may give some interesting perspective to consider, since a recent review (Hagstrom et al., 2020) where it was concluded that strength training for the upper body in women should be performed with 3-4 sets per exercise on 2-4 training days per week to stimulate maximal strength gains. Nevertheless, the present increases in maximal dynamic strength are somewhat similar to both earlier and recent studies obtained during 6-12 weeks of CON and/or ECC strength training in the lower extremities in women and men (Coratella et al., 2018;Roig et al., 2009;Coratella and Schena, 2016) and in the upper extremities in men (Häkkinen and Komi 1981). Coratella et al., (2021) showed recently that 8 weeks of CON, ECC and CON-ECC re-sistance training for knee extensor muscles in women increased both concentric and isometric torque similarly in all groups, whereas eccentric torque increased more in ECC than in CON. ...
Article
Full-text available
Effects of eccentric (ECC) versus concentric (CON) strength training of the upper body performed twice a week for 10 weeks followed by detraining for five weeks on maximal force, muscle activation, muscle mass and serum hormone concentrations were investigated in young women (n = 11 and n = 12). One-repetition bench press (1RM), maximal isometric force and surface electromyography (EMG) of triceps brachii (TB), anterior deltoid (AD) and pectoralis major (PM), cross-sectional area (CSA) of TB (Long (LoH) and Lateral Head (LaH)) and thickness of PM, as well as serum concentrations of free testosterone, cortisol, follicle-stimulating hormone, estradiol and sex hormone-binding globulin were measured. ECC and CON training led to increases of 17.2 ± 11.3% (p < 0.001) and 13.1 ± 5.7% (p < 0.001) in 1RM followed by decreases of -6.6 ± 3.6% (p < 0.01) and -8.0 ± 4.5% (p < 0.001) during detraining, respectively. Isometric force increased in ECC by 11.4 ± 9.6 % (p < 0.05) from week 5 to 10, while the change in CON by 3.9±6.8% was not significant and a between group difference was noted (p < 0.05). Maximal total integrated EMG of trained muscles increased only in the whole subject group (p < 0.05). CSA of TB (LoH) increased in ECC by 8.7 ± 8.0% (p < 0.001) and in CON by 3.4 ± 1.6% (p < 0.01) and differed between groups (p < 0.05), and CSA of TB (LaH) in ECC by 15.7 ± 8.0% (p < 0.001) and CON by 9.7 ± 6.6% (p < 0.001). PM thickness increased in ECC by 17.7 ± 10.9% (p < 0.001) and CON by 14.0 ± 5.9% (p < 0.001). Total muscle sum value (LoH + LaH + PM) increased in ECC by 12.4 ± 6.9% (p < 0.001) and in CON by 7.1 ± 2.9% (p < 0.001) differing between groups (p < 0.05) and decreased during detraining in ECC by -6.5 ± 4.3% (p < 0.001) and CON by -6.1 ± 2.8% (p < 0.001). The post detraining combined sum value of CSA and thickness was in ECC higher (p < 0.05) than at pre training. No changes were detected in serum hormone concentrations, but baseline free testosterone levels in the ECC and CON group combined correlated with changes in 1RM (r = 0.520, p < 0.016) during training. Large neuromuscular adaptations of the upper body occurred in women during ECC, and CON training in 10 weeks. Isometric force increased only in response to ECC, and total muscle sum value increased more during ECC than CON training. However, no changes occurred in serum hormones, but individual serum-free testosterone baseline concentrations correlated with changes in 1RM during strength training in the entire group. Both groups showed significant decreases in neuromuscular performance and muscle mass during detraining, while post detraining muscle sum value was only in ECC significantly higher than at pre training.
... The present investigation was conceived as parallel, four groups, pre-post, randomized controlled trial. Using a restricted blocked randomization (computer-generated sequence, proportion 1:1:1:1), the participants were randomized into four groups: concentric-only (CONC), eccentric-only (ECC), traditional concentric-eccentric training (TRAD), and control group (CON; Coratella and Schena, 2016). One of the researchers without any contact or knowledge of the participants completed the allocation and randomization of groups. ...
... Visual feedback (time = 1.5 s) was provided to the participants to maintain the required time under tension (Coratella et al., 2015a,b). Therefore, for each training session, CONC performed six sets × seven repetitions at 85%1-RM; ECC performed five sets × six repetitions at 120%1-RM; TRAD performed four sets × five repetitions at 90%1-RM, while CON did not train (Coratella and Schena, 2016). Knee extensors 1-RM was performed on the same device used for the training (Leg extension Technogym, Cesena, Italy), in line with previous procedures (Coratella and Bertinato, 2015;Coratella et al., 2015a,b). ...
... *p < 0.05 vs. Pre; a p < 0.05 vs. CON; and b p < 0.05 vs. CONC. autonomously by the participants without the help of any operator (Coratella and Schena, 2016). The intervention was performed on the dominant limb. ...
Article
Full-text available
The current randomized controlled study investigated whether or not the inclusion of the eccentric phase in resistance training favors the contralateral strength gains after different unilateral protocols, and whether such gains are retained after detraining. Sixty healthy women were randomly assigned to a unilateral concentric-only (CONC), eccentric-only (ECC), concentric–eccentric (TRAD) volume-equated knee extension training or control group (CON). The participants trained 2 days/week for 8 weeks and then did not train for further 8 weeks. Knee extensors isokinetic concentric, eccentric, and isometric peak torque and vastus lateralis muscle thickness were assessed in the contralateral limb at baseline, post-training, and post-detraining. At post-training, concentric peak torque increased in CONC [+9.2%, 95%CI (+6.2/+12.3), p < 0.001, ES: 0.70, 95%CI (0.01/1.39)], ECC [+11.0% (+7.7/+14.2), p < 0.001: ES: 0.66(0.09/1.23)] and TRAD [+8.5%(+5.7/+11.6), p < 0.001, ES: 0.50(0.02/0.98)]. Eccentric peak torque increased in ECC in ECC [+15.0%(+11.4/+20.7), p < 0.001, ES: 0.91(0.14/1.63)] and TRAD [+5.5%(+0.3/10.7), p = 0.013, ES: 0.50(0.05/0.95)]. Isometric peak torque increased in ECC [+11.3(+5.8/16.8), p < 0.001, ES: 0.52(0.10/0.94)] and TRAD [+8.6%(+3.4/+13.7), p < 0.001, ES: 0.55(0.14/0.96)]. No change in eccentric and isometric peak torque occurred in CONC ( p > 0.05). Muscle thickness did not change in any group ( p > 0.05). At post-detraining, all groups preserved the contralateral strength gains observed at post-training ( p < 0.05). The findings showed that ECC and TRAD increased contralateral knee extensors strength in concentric, eccentric, and isometric modality, while CONC only increased concentric strength. The eccentric phase appears to amplify the cross-education effect, permitting a transfer in strength gaining toward multiple testing modalities. Both eccentric-based and traditional eccentric–concentric resistance protocols are recommended to increase the contralateral retention in strength gains after a detraining period.
... A different approach is basing the resistance training on performing either the concentric or the eccentric phase alone. Because the intensity usable during both traditional and concentric-based training depends on the maximal concentric strength, in practice an eccentric-based training allows supramaximal loads to be used, thus increasing the long-term mechanical stimuli (17,20). Notwithstanding, when performed in a volume-equated program (i.e., the combination of the load, load displacement, number of repetitions, and time under tension) (14), similar strength gains were reported after an eccentric-based, concentric-based, and traditional eccentric-concentric training, although the eccentricbased training was the only one that promoted a hypertrophic response (20). ...
... Because the intensity usable during both traditional and concentric-based training depends on the maximal concentric strength, in practice an eccentric-based training allows supramaximal loads to be used, thus increasing the long-term mechanical stimuli (17,20). Notwithstanding, when performed in a volume-equated program (i.e., the combination of the load, load displacement, number of repetitions, and time under tension) (14), similar strength gains were reported after an eccentric-based, concentric-based, and traditional eccentric-concentric training, although the eccentricbased training was the only one that promoted a hypertrophic response (20). However, strength was assessed only as 1 repetition maximum (1RM), whereas it was observed that concentric-based or eccentric-based training led to greater specific increases in the concentric and eccentric strength, respectively (5). ...
... As such, including a more comprehensive strength evaluation by assessing concentric, eccentric, and isometric strength may provide further information about the capacity of each protocol to stimulate different strength exertion modalities (40). In addition, because the hypertrophic response was assessed indirectly as muscle girth (20), more accurate techniques and devices (e.g., lean mass assessed by dual X-ray absorptiometry [DXA] or muscle thickness by ultrasound) could be used to deepen this aspect (17). ...
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Coratella, G, Beato, M, Bertinato, L, Milanese, C, Venturelli, M, and Schena, F. Including the eccentric phase in resistance training to counteract the effects of detraining in women: a randomized controlled trial. J Strength Cond Res XX(X): 000-000, 2021-The current study compared the effects of concentric-based (CONC), eccentric-based (ECC), and traditional concentric-eccentric (TRAD) resistance training on muscle strength, mass, and architecture and the postdetraining retention of the training-induced effects in women. Sixty women were randomly assigned to unilateral volume-equated CONC, ECC, or TRAD knee extension training or control (N = 15 per group). Before training, after an 8-week intervention period, and after an 8-week detraining period, isokinetic concentric, eccentric, and isometric torque were measured. In addition, thigh lean mass was assessed by dual X-ray absorptiometry and vastus lateralis thickness, pennation angle, and fascicle length by ultrasound. After training, concentric and isometric torque increased (p < 0.05) similarly in all groups, whereas eccentric torque increased more in ECC than that in CONC (+13.1%, effect size (ES): 0.71 [0.04-1.38]) and TRAD (+12.6%, ES: 0.60 [0.12-1.08]). Thigh lean mass increased in ECC (+6.1%, ES: 0.47 [0.27-0.67]) and TRAD (+3.1%, ES: 0.33 [0.01-0.65]). Vastus lateralis thickness and pennation angle increased (p < 0.05) similarly in all groups, whereas fascicle elongation was visible in ECC (+9.7%, ES: 0.92 [0.14-1.65]) and TRAD (+7.1%, ES: 0.64 [0.03-1.25]). After detraining, all groups retained (p < 0.05) similar concentric torque. ECC and TRAD preserved eccentric torque (p < 0.05), but ECC more than TRAD (+17.9%, ES: 0.61 [0.21-1.21]). All groups preserved isometric torque (p < 0.05), but ECC more than CONC (+14.2%, ES: 0.71 [0.04-1.38]) and TRAD (+13.8%, ES: 0.65 [0.10-1.20]). Thigh lean mass and vastus lateralis fascicle length were retained only in ECC (p < 0.05), pennation angle was preserved in all groups (p < 0.05), and thickness was retained in CONC and ECC (p < 0.05). Including the eccentric phase in resistance training is essential to preserve adaptations after detraining.
... However, limited information is available for the effect of detraining after ET versus CT training on the trained and contralateral non-trained muscles. Coratella and Schena [8] compared the detraining effect of bench press exercise on pectoral muscles after ET (5 sets × 6 repetitions at 120 % of one repetition maximum: 1-RM), CT (6 sets × 7 repetitions at 85 % 1-RM), and traditional (concentric and eccentric) resistance training (4 sets × 5 repetitions at 90 % 1-RM) that were performed twice a week for 6 weeks. They showed that muscle strength and hypertrophy were maintained during the 6 weeks of detraining after ET, but not after CT and traditional resistance training. ...
... This suggests greater muscle hypertrophy after ET than CT. The effects of ET versus CT on muscle hypertrophy are controversial [30], but some studies have shown greater muscle hypertrophy after ET than CT [8,12,31], which is in line with the finding of the present study. For example, Farthing and Chilibeck [12] showed 13 % increase in MT of biceps brachii plus brachialis after the fast velocity isokinetic ET but not after CT of the elbow flexors performed three times a week for 8 weeks (24 sessions in total). ...
... It seems likely that the smaller increase in MT in the present study was due to the smaller number of training sessions. Regarding the non-significant increase in MT after CT, Coratella and Schena [8] also showed no muscle hypertrophy after CT and traditional (concentric and eccentric) RT. It has been reported that the expression of insulin-like growth factors and mechano-growth factors is smaller after CT than ET [18]. ...
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Abstract Background Unilateral resistance training increases the strength of the contralateral non-trained homologous muscles known as the cross-education effect. We tested the hypothesis that unilateral eccentric resistance training (ET) would induce greater and longer-lasting cross-education effect when compared with concentric resistance training (CT). Methods Young (20–23 y) participants were allocated to ET (5 males, 4 females) or CT (5 males, 4 females) group that performed unilateral progressive ET or CT of the elbow flexors, twice a week for 5 weeks (10 sessions) followed by a 5-week detraining, and control group (7 males, 6 females) that did not perform any training. Maximum voluntary isometric contraction torque of the elbow flexors (MVIC), one-repetition maximum of concentric dumbbell curl (1-RM), and biceps brachii and brachialis muscle thickness (MT) were measured from the trained and non-trained arms before, several days after the last training session, and 5 weeks later. A ratio between the trained and non-trained arms for the change in MVIC or 1-RM from pre- to post-training (cross-body transfer ratio) was compared between ET and CT groups. Results The control group did not show significant changes in any variables. Both ET and CT increased (P 0.05) after ET and CT, and MVIC returned to the baseline after detraining, but 1-RM was maintained for both groups. An increase (P
... Resistance exercise training (RET) is the one greatest strategy to counteract skeletal muscle dysfunction [56]. RET can be performed with different modalities, for example, changing number of repetitions, number of sets, rest time, speed of movement and modifying the load in the eccentric face [57][58][59][60][61]. Traditionally, it is recommended to perform heavy-load contractions (i.e. ...
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Coronavirus disease 2019 (COVID-19) is a worldwide pandemic illness that is impacting the cardiovascular, pulmonary, musculoskeletal, and cognitive function of a large spectrum of the worldwide population. The available pharmacological countermeasures of these long-term effects of COVID-19 are minimal, while myriads of non-specific non-pharmacological treatments are emerging in the literature. In this complicated scenario, particular emphasis should be dedicated to specific exercise interventions tailored for subjects and athletes recovering from COVID-19. Specific guidelines on adapted physical activity in this critical population are unavailable so far, therefore, in this position statement of the Società Italiana di Scienze Motorie e Sportive (SISMeS) the members of the steering committee of the research group Attività Motoria Adattata, Alimentazione, Salute e Fitness have indicated the adapted physical activity approaches to counteract the long-term effects of the COVID-19, both in good health people and athletes.
... Therefore, long-term OS usage may lead to not only a reduction in myofascial pain but also an enhancement of body flexibility. Second, no studies investigated possible OS influences on strength-endurance, an important aspect of force-generating capacity, which is essential for both sport performance and daily life activities [23]. The possible higher relaxation level or over-involvement of the temporo-mandibular muscles induced by OS usage may conceivably contribute to a better muscular performance while exerting a strength-endurance task. ...
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Purpose We investigated the acute and chronic effects of oral splint on muscle strength-endurance performance and body flexibility. Methods Twelve Pilates practitioners (age 49.5 ± 5.8 years; mass 58.6 ± 6.5 kg) were evaluated with (OS) and without (CTRL) oral splint. Before (PRE) and after (POST) 8 weeks of oral splint usage during Pilates activity, muscle strength-endurance and body flexibility were evaluated through a frontal plank exercise and a Toe-touch test in OS and CTRL. Before each test, the highest electrical activation (EMG) of masseter and temporal muscles during maximal occlusion was determined. During frontal plank, the time-to-exhaustion, the maximum voluntary activation of masticatory muscles and the time of muscles activation have been determined. Results No OS vs CTRL and PRE vs POST differences were found in the maximum voluntary activation of temporal and masseter muscles. The time-to-exhaustion in OS was longer than CTRL in both PRE ( P = 0.049) and POST sessions ( P = 0.043). Time of masticatory muscles activation during plank was moderately greater in OS at PRE ( P = 0.020) and POST ( P = 0.022), while no difference between PRE and POST emerged in both conditions. Higher muscular activation was found in OS than CTRL at PRE ( P = 0.031) and POST ( P = 0.031), whereas no difference between PRE and POST appeared. No effect on flexibility emerged neither acutely nor chronically. Conclusion Acute and chronic oral splint usage improved strength-endurance performance but not body flexibility. These findings suggest biomechanical and neural mechanisms influencing the muscle length and the concurrent activation potentiation, but not muscle tone and stiffness.
... Descriptive statistics are shown in Table 1 for all subjects. A priori power analysis was conducted using G*Power (version 3.1, Universität Kiel, Germany), using previously published data with AEL training (5) indicated that a total of 5 subjects were needed to find a large effect (d 5 1.52) with power (1 2 b) set at 0.87 and a of 0.05. All recruited subjects had been actively competing in powerlifting regional, state, and national competitions for at least 2 years. ...
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Effects of augmented eccentric load bench press training on one repetition maximum performance and electromyographic activity in trained powerlifters. J Strength Cond Res 35(6): 1512–1519, 2021—Augmented eccentric load (AEL) training has been shown to elicit greater lower-body muscular strength increases and faster performance improvements compared with traditional strength training. However, it is unknown whether AEL training could provide similar improvements in upper-body muscular strength. Therefore, this study investigated the effects of a 4- week AEL training program on bench press one repetition maximum (1RM) strength, bar kinetics and kinematics, and surface electromyography (EMG) activity. Eight competitive powerlifters completed 5 training sessions consisting of 7 sets of a single repetition with up to 5 minutes rest between sets. Each session was completed at a predetermined AEL percentage consisting of 90% 1RM for concentric and supramaximal loads ranging from 105 to 125% 1RM during the eccentric phase with the use of eccentric hooks. After 4 weeks of AEL training, 1RM performance significantly increased from pretest to posttest (116.62 6 27.48–124.28626.96 kg, p50.001). In addition, EMG amplitude of the pectoralis major decreased during the 125% AEL session to 59.86 6 15.36% of pretest 1RM EMG values (p 5 0.049, effect sizes [ESs] 5 0.69). Furthermore, peak power of 1RM increased by 36.67% from pretest to posttest (p 5 0.036, ES 5 0.58). These study findings suggest that incorporating AEL bench press training into a 4-week training cycle may be a novel strategy to improve 1RM performance in competitive powerlifters in a short period.
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Background Frailty is a complex geriatric syndrome and serves as an indicator for functional degradation in older adults. Regular exercise intervention could reduce the level of frailty and improve general physical fitness. The aim of this study was to test the effects of the Vitality Acupunch (VA) exercise on the promotion of physical fitness and the improvement of frailty status among frail older adults in long-term care facilities. Method This study was a cluster-randomized controlled trial adopted a pretest-posttest design. Using convenience sampling, 81 frail adults older than 65 years of age from 10 long-term care facilities participated in this study. The older adults were cluster-randomized by facility into an intervention group (5 long-term care facilities, n = 40) and a control group (5 long-term care facilities, n = 41). The intervention group engaged in the VA exercise 3 times a week, each lasting 40 min, for 24 weeks. The control group maintained regular activities of daily living. The outcome measures for physical fitness were assessed before study began (pretest), at the 12th week (posttest 1), and at the 24th week (posttest 2) in the study. Results After a 24-week intervention, the frail older adults who engaged in the VA exercise program showed significant improvements in handgrip strength, upper-limb muscle endurance, lung function, shoulder flexibility, forward flexion, shoulder joint flexion, and shoulder joint abduction (all p < .05) but not in lower-limb muscle endurance (p = .502) compared against their pretest data. The intervention group had significantly better physical fitness and positive changes in frailty status than the control group (all p < .001), except for the lower-limb muscle endurance (p = .557). Conclusion Regular engagement in the VA exercise program for 24 weeks significantly improved the physical fitness and frailty status of frail older adults in long-term care facilities.
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The present study examined the posterior chain muscle excitation in different deadlift variations. Ten competitive bodybuilders (training seniority of 10.6 ± 1.8 years) performed the Romanian (RD), Romanian standing on a step (step-RD), and stiff-leg deadlift (SD) with an 80% 1-RM. The excitation of the gluteus maximus, gluteus medius, biceps femoris, semitendinosus, erector spinae longissimus, and iliocostalis was assessed during both the ascending and descending phases. During the ascending phase, the RMS of the gluteus maximus was greater in the step-RD than in the RD (effect size (ES): 1.70, 0.55/2.84) and SD (ES: 1.18, 0.11/2.24). Moreover, a greater RMS was found in the SD than in the RD (ES: 0.99, 0.04/1.95). The RMS of the semitendinosus was greater in the step-RD than in the RD (ES: 0.82, 0.20/1.44) and SD (ES: 3.13, 1.67/4.59). Moreover, a greater RMS was found in the RD than in the SD (ES: 1.38, 0.29/2.48). The RMS of the longissimus was greater in the step-RD than in the RD (ES: 2.12, 0.89/3.34) and SD (ES: 3.28, 1.78/4.78). The descending phase had fewer differences between the exercises. No further differences between the exercises were found. The step-RD increased the overall excitation of the posterior chain muscles, possibly because of the greater range of movement and posterior muscle elongation during the anterior flexion. Moreover, the RD appeared to target the semitendinosus more than the SD, while the latter excited the gluteus maximus more.
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We recently reported that the greatest distinguishing feature between eccentric (ECC) and concentric (CON) muscle loading lays in architectural adaptations: ECC favors increases in fascicle length (Lf), associated with distal vastus lateralis muscle (VL) hypertrophy, and CON increases in pennation angle (PA). Here, we explored the interactions between structural and morphological remodeling, assessed by ultrasound and dual x-ray absorptiometry (DXA), and long-term muscle protein synthesis (MPS), evaluated by deuterium oxide (D2O) tracing technique. Ten young males (23 ± 4 years) performed unilateral resistance exercise training (RET) three times/week for 4 weeks; thus, one-leg trained concentrically while the contralateral performed ECC exercise only at 80% of either CON or ECC one repetition maximum (1RM). Subjects consumed an initial bolus of D2O (150 mL), while a 25-mL dose was thereafter provided every 8 days. Muscle biopsies from VL midbelly (MID) and distal myotendinous junction (MTJ) were collected at 0 and 4-weeks. MPS was then quantified via GC–pyrolysis–IRMS over the 4-week training period. Expectedly, ECC and CON RET resulted in similar increases in VL muscle thickness (MT) (7.5% vs. 8.4%, respectively) and thigh lean mass (DXA) (2.3% vs. 3%, respectively), albeit through distinct remodeling: Lf increasing more after ECC (5%) versus CON (2%) and PA increasing after CON (7% vs. 3%). MPS did not differ between contractile modes or biopsy sites (MID-ECC: 1.42 vs. MID-CON: 1.4% day−1; MTJ-ECC: 1.38 vs. MTJ-CON: 1.39% day−1). Muscle thickness at MID site increased similarly following ECC and CON RET, reflecting a tendency for a contractile mode-independent correlation between MPS and MT (P = 0.07; R2 = 0.18). We conclude that, unlike MT, distinct structural remodeling responses to ECC or CON are not reflected in MPS; the molecular mechanisms of distinct protein deposition, and/or the role of protein breakdown in mediating these responses remain to be defined. © 2015 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of the American Physiological Society and The Physiological Society.
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Unlabelled: We recently reported that the greatest distinguishing feature between eccentric (ECC) and concentric (CON) muscle loading lays in architectural adaptations: ECC favors increases in fascicle length (Lf), associated with distal vastus lateralis muscle (VL) hypertrophy, and CON increases in pennation angle (PA). Here, we explored the interactions between structural and morphological remodeling, assessed by ultrasound and dual x-ray absorptiometry (DXA), and long-term muscle protein synthesis (MPS), evaluated by deuterium oxide (D2O) tracing technique. Ten young males (23 ± 4 years) performed unilateral resistance exercise training (RET) three times/week for 4 weeks; thus, one-leg trained concentrically while the contralateral performed ECC exercise only at 80% of either CON or ECC one repetition maximum (1RM). Subjects consumed an initial bolus of D2O (150 mL), while a 25-mL dose was thereafter provided every 8 days. Muscle biopsies from VL midbelly (MID) and distal myotendinous junction (MTJ) were collected at 0 and 4-weeks. MPS was then quantified via GC-pyrolysis-IRMS over the 4-week training period. Expectedly, ECC and CON RET resulted in similar increases in VL muscle thickness (MT) (7.5% vs. 8.4%, respectively) and thigh lean mass (DXA) (2.3% vs. 3%, respectively), albeit through distinct remodeling: Lf increasing more after ECC (5%) versus CON (2%) and PA increasing after CON (7% vs. 3%). MPS did not differ between contractile modes or biopsy sites (MID-ECC: 1.42 vs. Mid-con: 1.4% day(-1); MTJ-ECC: 1.38 vs. Mtj-con: 1.39% day(-1)). Muscle thickness at MID site increased similarly following ECC and CON RET, reflecting a tendency for a contractile mode-independent correlation between MPS and MT (P = 0.07; R(2) = 0.18). We conclude that, unlike MT, distinct structural remodeling responses to ECC or CON are not reflected in MPS; the molecular mechanisms of distinct protein deposition, and/or the role of protein breakdown in mediating these responses remain to be defined.
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The aim of this study was to evaluate the effects of unilateral eccentric training using constant velocity or constant external load on untrained limb. Forty-nine participants were randomized in isokinetic (IK), dynamic constant external resistance (DCER) unilateral eccentric training or control groups. Knee-extension 1RM and isometric, eccentric and concentric knee extensors' peak torques, as well as changes in vastus lateralis muscle thickness, fascicle length, pennation angle and quadriceps fat-free mass were measured. After training, both IK and DCER similarly increased over time 1RM (respectively, ?3.6 kg, CI 95 % 0.6–6.5 and ?4.3 kg, CI 95 % 1.6–6.9), concentric (respectively, ?8.4 N/m, CI 95 % 0.0 to ?16.4 and 9.8 CI 95 % 0.6–19.2), eccentric (respectively, ?28.5 N/m, CI 95 % 11.0 to ?46.0 and 21.1 CI 95 % 15.1–37.0), and isometric (respectively, ?15.4 N/m, CI 95 % 0.7–30.0 and ?13.9, CI 95 % 0.3–27.5) peak torques. No increase was found for vastus lateralis muscle thickness , fascicle length, pennation angle and quadriceps fat-free mass. Eccentric training was effective for inducing strength, but not structural, adaptations in untrained limb. Both in rehabilitation and training practice, use of easily available gym devices can be a good substitute for expensive and often unavailable isokinetic devices.
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Aim of the study was to compare the effects of unilateral eccentric-only training using constant velocity vs. constant external load. Forty-seven participants were randomized in isokinetic (IK), dynamic constant external resistance (DCER) unilateral eccentric training or control groups. Knee extension 1RM and isometric, eccentric and concentric knee extensors peak torque, as well as changes in vastus lateralis fascicle pennation angle, fascicle length, muscle thickness, and quadriceps fat-free mass were measured. Both IK and DCER training consisted in 5 × 8 eccentric-only repetitions, 2d/w, for 6 weeks. IK and DCER training sessions were matched for total volume. After training, both IK and DCER similarly increased 1RM (respectively, +4.4 kg, CI95% 1.8-7.0 and +5.5 kg, CI95% 3.3-7.9), isometric (respectively, +34.5 N/m, CI95% 23.0-45.9 and +15.8, CI95% 5.4-26.2) and concentric peak torque (respectively, +17.0 N/m, CI95% 6.6 to +27.4 and 12.2 CI95% 2.8-21.7). IK increased eccentric peak torque significantly more than DCER (respectively, +84.2 N/m, CI95% 66.3-102.1 and +38.2 N/m, CI95% 21.9-54.4). Both IK and DCER similarly increased fascicle length (respectively, +14.7 mm, CI95% 5.4-24.0 and +14.4 mm, CI95% 5.4-23.3) and muscle thickness (respectively, +3.3 mm, CI95% 1.5-5.1, and +4.1 mm, CI95% 2.5-5.7). Matching the training volume resulted in similar adaptations comparing eccentric-only IK or DCER resistance training. Both in rehabilitation and in training practice, the use of easily available gym devices can be a good substitute for expensive and often unavailable IK devices.
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It is generally accepted that neural factors play an important role in muscle strength gains. This article reviews the neural adaptations in strength, with the goal of laying the foundations for practical applications in sports medicine and rehabilitation. An increase in muscular strength without noticeable hypertrophy is the first line of evidence for neural involvement in acquisition of muscular strength. The use of surface electromyographic (SEMG) techniques reveal that strength gains in the early phase of a training regimen are associated with an increase in the amplitude of SEMG activity. This has been interpreted as an increase in neural drive, which denotes the magnitude of efferent neural output from the CNS to active muscle fibres. However, SEMG activity is a global measure of muscle activity. Underlying alterations in SEMG activity are changes in motor unit firing patterns as measured by indwelling (wire or needle) electrodes. Some studies have reported a transient increase in motor unit firing rate. Training-related increases in the rate of tension development have also been linked with an increased probability of doublet firing in individual motor units. A doublet is a very short interspike interval in a motor unit train, and usually occurs at the onset of a muscular contraction. Motor unit synchronisation is another possible mechanism for increases in muscle strength, but has yet to be definitely demonstrated. There are several lines of evidence for central control of training-related adaptation to resistive exercise. Mental practice using imagined contractions has been shown to increase the excitability of the cortical areas involved in movement and motion planning. However, training using imagined contractions is unlikely to be as effective as physical training, and it may be more applicable to rehabilitation. Retention of strength gains after dissipation of physiological effects demonstrates a strong practice effect. Bilateral contractions are associated with lower SEMG and strength compared with unilateral contractions of the same muscle group. SEMG magnitude is lower for eccentric contractions than for concentric contractions. However, resistive training can reverse these trends. The last line of evidence presented involves the notion that unilateral resistive exercise of a specific limb will also result in training effects in the unexercised contralateral limb (cross-transfer or cross-education). Peripheral involvement in training-related strength increases is much more uncertain. Changes in the sensory receptors (i.e. Golgi tendon organs) may lead to disinhibition and an increased expression of muscular force. Agonist muscle activity results in limb movement in the desired direction, while antagonist activity opposes that motion. Both decreases and increases in co-activation of the antagonist have been demonstrated. A reduction in antagonist co-activation would allow increased expression of agonist muscle force, while an increase in antagonist co-activation is important for maintaining the integrity of the joint. Thus far, it is not clear what the CNS will optimise: force production or joint integrity. The following recommendations are made by the authors based on the existing literature. Motor learning theory and imagined contractions should be incorporated into strength-training practice. Static contractions at greater muscle lengths will transfer across more joint angles. Submaximal eccentric contractions should be used when there are issues of muscle pain, detraining or limb immobilisation. The reversal of antagonists (antagonist-to-agonist) proprioceptive neuromuscular facilitation contraction pattern would be useful to increase the rate of tension development in older adults, thus serving as an important prophylactic in preventing falls. When evaluating the neural changes induced by strength training using EMG recording, antagonist EMG activity should always be measured and evaluated.
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Purpose This study compared the exercise induced muscle damage and repeated bout effect after isoload vs isokinetic eccentric supra-maximal single session. Methods Thirty sport science male students were ran-domly divided in isokinetic (IK) and isoload (IL) eccentric training. Creatin kinase (CK) serum activity, muscle sore-ness and strength decrement measured both in dynamic and isometric modalities were recorded at baseline, immedi-ately after and up to 4 days following 48 supramaximal IK or IL eccentric contractions. Same protocol was repeated after 4 weeks. A three-way repeated measures ANOVA was used to detect differences in dependent variables comparing group 9 bout 9 time. Results No three-way interaction occurred in dependent variables. Bout 9 time resulted in a significant interaction in all dependent variables. Muscle damage markers resul-ted significantly altered compared to baseline up to 4 days. However, IL showed significantly greater CK, muscle soreness and strength deficit compared to IK. All parame-ters were significantly reduced after second compared to first bout. Difference between IL and IK after second bout was not overall significant. Conclusion IK vs IL supra-maximal eccentric contraction is showed to have different muscle damage symptoms. Protection conferred by first bout reduced muscle damage after 4 weeks and decreased difference between IL and IK.
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Memory is a process in which information is encoded, stored, and retrieved. For vertebrates, the modern view has been that it occurs only in the brain. This review describes a cellular memory in skeletal muscle in which hypertrophy is 'remembered' such that a fibre that has previously been large, but subsequently lost its mass, can regain mass faster than naive fibres. A new cell biological model based on the literature, with the most reliable methods for identifying myonuclei, can explain this phenomenon. According to this model, previously untrained fibres recruit myonuclei from activated satellite cells before hypertrophic growth. Even if subsequently subjected to grave atrophy, the higher number of myonuclei is retained, and the myonuclei seem to be protected against the elevated apoptotic activity observed in atrophying muscle tissue. Fibres that have acquired a higher number of myonuclei grow faster when subjected to overload exercise, thus the nuclei represent a functionally important 'memory' of previous strength. This memory might be very long lasting in humans, as myonuclei are stable for at least 15 years and might even be permanent. However, myonuclei are harder to recruit in the elderly, and if the long-lasting muscle memory also exists in humans, one should consider early strength training as a public health advice. In addition, myonuclei are recruited during steroid use and encode a muscle memory, at least in rodents. Thus, extending the exclusion time for doping offenders should be considered.
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This study determined the contribution of extracellular matrix (ECM) remodeling to the protective adaptation of human skeletal muscle known as the repeated-bout effect (RBE). Muscle biopsies were obtained 3 hours, 2 days, and 27 days following an initial bout (B1) of lengthening contractions (LCs) and 2 days following a repeated bout (B2) in 2 separate studies. Biopsies from the nonexercised legs served as controls. In the first study, global transcriptomic analysis indicated widespread changes in ECM structural, deadhesive, and signaling transcripts, 3 hours following LC. To determine if ECM remodeling is involved in the RBE, we conducted a second study by use of a repeated-bout paradigm. TNC immunoreactivity increased 10.8-fold following B1, was attenuated following B2, and positively correlated with LC-induced strength loss (r(2) = 0.45; P = 0.009). Expression of collagen I, III, and IV (COL1A1, COL3A1, COL4A1) transcripts was unchanged early but increased 5.7 ± 2.5-, 3.2 ± 0.9-, and 2.1 ± 0.4-fold (P < 0.05), respectively, 27 days post-B1 and were unaffected by B2. Likewise, TGF-β signaling demonstrated a delayed response following LC. Satellite cell content increased 80% (P < 0.05) 2 days post-B1 (P < 0.05), remained elevated 27 days post-B1, and was unaffected by B2. Collectively, the data suggest sequential ECM remodeling characterized by early deadhesion and delayed reconstructive activity that appear to contribute to the RBE.-Hyldahl, R. D., Nelson, B., Xin, L., Welling, T., Groscost, L., Hubal, M. J., Chipkin, S., Clarkson, P. M., Parcell, A. C. Extracellular matrix remodeling and its contribution to protective adaptation following lengthening contractions in human muscle. © FASEB.